Traumatic acute subdural haematoma (TASH) is one of the lethal causes following severe head injuries. Traumatic acute subdural haematoma occurs in about 10–20% of patients with severe head injuries .
The haematomas commonly have a high mortality rate (between 40 and 60%). This high rate of mortality may be due to the haematoma, primary brain injury at the moment of impact, and subsequent changes due to hypotension and hypoxia .
Isolated TASH means it is not associated with other haematomas like epidural, subarachnoid or intracerebral ones. It only occurs in 30–40% of TASH .
In the current paper, we reported and studied 39 patients with isolated TASH who were admitted and managed in the trauma Unit of Assiut university Hospital over a period of one year (from 1/9/2019 to 31/8/2020).
Age of patients ranged from 9 to 75 years. The mean age was 38.025 years. Patients from 9 to 30 years were 17 (41%), from 31 to 55 were 16 (41%) and from 56 to 75 years were 7 patients (18%). There were 28 male (71.79%) and 11 females (28.20%). We reported that death occurred at the age of 9–30 years were 4, poor outcome (GOS 2, 3) in 4 and favourable outcome (GOS 4, 5) were in 9 patients. In the age group from 31 to 55 years, death was in 7, poor outcome in 7 and favourable in 2 patients.
There was a highly significant correlation (p-value 0.003) between the age of patient and GOS, as poor outcome was found in patients with a mean age of 47.18 years while favourable outcome was reported in patients with a mean age 26.27 years. Our findings are in agreement with those of Hanif et al.  as they reported significant mortality in older patients (50% over 70 years of age, 25.6% between 40 and 70 years, and 26% below 40 years).
Our findings are in agreement with those of Ono and colleagues , who found a statistically significant correlation between age and patient outcome.
Amato and colleagues  in his study of 28 patients with isolated TASH concluded the same findings. Yılmaz and colleagues  in their study of 93 patients with TASH who underwent decompressive craniectomy, they found that older age were statistically significant with mortality rate (p-value 0.007). However, Chen et al.  said that age has no statistically significant association with functional outcomes.
Glasgow Coma Scale (GCS) is the most important indicator that reflects the degree of brain injury and reflects the patient's neurological status on admission and during follow-up .
In the present study, upon admission, 4 patients (10.25%) had GCS greater or equal to 13 (mild brain injury), GCS between 9 and 12 was found in 15 patients (38.46%) with moderate brain injury while 20 patients (51.28%) had GCS less than or equal to 8 (severe brain injury). Among the 20 patients with GCS less or equal 8, death occurred in 12 patients (60%) while poor outcome was reported in 6 patients (30%) and favourable outcome was found only in 2 patients (10%). Among 15 patients with GCS 9 to 12 with moderate brain injury, death happened in 5 patients (33.3%), poor outcome in 5 patients (33.3%), while favourable outcome was reported in 5 patients (33.3%).
In 4 patients with GCS 13–15 (mild brain injury), no death reported, and all 4 patients had a favourable outcome (100%).
In the current study, there was a highly statistically significant correlation between patients' GOS outcome and GCS upon admission (p-value 0.006). Aykut and colleagues  reported that among 57 patients with GCS 3–8, 40 died (70.2%) and a favourable outcome was found in 4 patients (7%), whereas in 35 patients with GCS 9–12, death occurred in 19 (54.3) and favourable recovery was reported in 19 patients (28.5%). Among 21 patients with GCS 13–15, death was reported in 5 (23.8%), while a favourable recovery was found in 16 patients (76.2%). Moreover, they reported a strong correlation between GCS score in admission and outcome. These findings agree with the findings of the current study. Phuenpathom and colleagues  concluded that GSC score is one of the most critical factors predicting the outcome in patients with TASH. However, Chin et al.  demonstrated that higher GCS score did not affect the outcome, which can be attributed to the exclusion criteria in their study, as they excluded patients with GCS 3 or 4 combined with bilateral pupil dilation. These reasons reduced the impact of the GCS score on the outcome of their study.
CT is the main diagnostic aid in TASH. Classic SDHs usually presented in one or two brain areas like parietal or temporoparietal area, however it can be spread over an entire hemisphere. In the early phase (hyperacute phase), TASH may be isodense as it is still liquid. Then, it coagulates and condenses during the acute phase and shows a typical hyperdense crescent-appearance in CT .
In the current study, out of 39 patients with isolated TASH, the thickness of the haematoma in 17 (43.58%) patients was less than 10 mm, while the thickness of the haematoma in 22 patients (56.41%) was equal or more than 10 mm.
In 22 patients with a haematoma thickness upon CT admission equal to or more than 10 mm, 10 (45.5%) died, 8 (36.4%) had a poor outcome, while favourable outcome was reported in 4 (18.2%) patients. However, there was a non-statistically significant relationship between admission CT and GOS (p value 0.220).
This may be attributed to those accidents with acceleration and deceleration effect lead to displacement of the neural tissue and damage that not commensurate with CT finding upon admission.
Of the 39 patients with TASH, 14 (35.89%) were treated conservatively. We based the selection of these patients on that haematoma thickness during admission with CT less than 10 mm or patients who were clinically stable or improved during observation. Five of these 14 (35.71%) died during the follow-up period (up to 6 weeks of admission). We reported 3 patients who subsequently needed surgery, nonetheless, due to the statistical analysis they were included with patients who were surgically treated.